The present invention relates generally to insulated shipping containers and relates more particularly to insulated shipping containers of the type which are formed at least in part of foamed polymer material.
Conventional insulated shipping containers of the so-called box-within-a-box configuration are well-known. These conventional box-within-a-box containers typically have an outer box formed of corrugated cardboard and a smaller, open-topped, inner box also formed of corrugated cardboard, the outer and inner boxes defining a void space therebetween. During manufacture of such shipping containers, the void space is filled with a foamed-in-place polymer material, said foamed-in-place polymer material typically being a light-to-medium density foamed polyurethane material.
Typically, the manufacture of such box-within-a-box containers comprises mounting the inner box, in an inverted position, over a manufacturing fixture having an upstanding plug member. Next, the outer box is inverted onto the manufacturing fixture with its top closure flaps turned outward, and its bottom closure flaps opened. The manufacturing fixture includes an outer movable wall structure which supports the side walls of the outer box. The polymer material in a liquid pre-foamed condition is then sprayed or poured into the void space between the two boxes and is allowed to foam in place. The foaming of the polymer material takes a sufficient period of time that the bottom closure flaps of the box may be closed before the foam fills the entirety of the void space, and a lid is closed over these closure flaps to support the box against the internal pressure created by the foaming polymer. As this polymer material foams in place, it bonds to both the inner and outer boxes and exerts a considerable pressure against both the inner and outer boxes. In fact, were it not for the support to these boxes provided by the manufacturing fixture, the boxes would be seriously distorted or destroyed by the foam pressure. After an additional period of time (total time of ten minutes or less), the foam hardens sufficiently that the substantially finished shipping container may be removed from the fixture.
In using such conventional insulated shipping containers, it is common for one or more articles being shipped therein to be inserted into the inner box of the container, together with dry ice or other temperature stabilizing packs and packing material. A form-fitting block of comparatively thick, open-cell foam is then inserted into the opening of the inner box. This open-cell foam serves as a thermal insulator and prevents the infusion of ambient air into the inner box and the escape of temperature-controlled air from within the inner box. Next, the top closure flaps of the outer box are closed and taped, and the shipping container is ready for shipment with the attachment of a shipping label thereto.
Unfortunately, the above-described conventional insulated shipping container has certain shortcomings. One significant shortcoming is that the materials of the container are not recyclable because the foamed polymer material bonds directly to the inner and outer cardboard boxes and cannot thereafter easily be separated therefrom. This shortcoming is an ever-increasing concern as more and more states and countries require that shipping materials which have destinations within their jurisdictions be recyclable or otherwise be subject to a penalty tax or fee for special disposal. Moreover, if the outer box becomes damaged or otherwise marked, it cannot be replaced in such a way as to permit the container to be reused.
One suggestion that has been proposed to allow the separation of foamed polymer material from the cardboard boxes of the aforementioned type of container has been to simply bunch a flat sheet of plastic film within the outer box and over the inner box before the foam polymer material in a liquid form is injected. However, the bunching of a flat sheet of plastic film in the above-described manner typically results in the formation of many folds and fissures in the excess sheet material. These many folds and fissures often form many airflow pathways through which temperature-controlled air can escape from the container, and through which ambient air can enter. Also, as can readily be appreciated, the aforementioned bunching of the plastic film typically results in variations in the thickness of the insulative foamed polymer in the vicinity of said folds and fissures. As a result, some containers made by this method possess one or more areas where the insulating foam is too thin and where, in effect, the contents are exposed to “hot spots” or “cold spots” of ambient air leaking into the container. Because one potential application of insulated shipping containers is in the transport of temperature-sensitive medical specimens or materials which are irreplaceable or critical to the well-being of a patient, the risks associated with using a shipping container made using a bunched flat sheet in the above-described manner are often too great.
In U.S. Pat. No. 5,897,017, inventor Lantz, which issued Apr. 27, 1999, and in U.S. Pat. No. 6,257,764, inventor Lantz, which issued Jul. 10, 2001, both of which are incorporated herein by reference, there is disclosed a recyclable insulated shipping container that addresses many of the above-described shortcomings associated with the use of a bunched flat sheet to separate foamed polymer material from a cardboard box. More specifically, the two Lantz patents above disclose an insulated shipping container that includes a specially-designed plastic bag into which the foam polymer material in a liquid form is injected to yield a body of foamed polymer material substantially contained within the specially-designed plastic bag, the body of foamed polymer material defining a chamber therein and an opening outwardly from the chamber surrounded by a transition surface, the specially-designed plastic bag including a rectangular end portion and a curved transition section extending from the rectangular end portion to a transverse line at which the bag defines a hoop dimension sufficient to allow the bag to extend across the transition surface of the body of foamed polymer material.
Because of its tailored shape, the Lantz bag has a minimal number of folds and fissures and, therefore, results in a body of foamed polymer material that is substantially uniformly thick and substantially free of fissures. Unfortunately, as can readily be appreciated, because of its unusual shape, the Lantz bag can be expensive to manufacture, thereby resulting in a shipping container that is expensive to manufacture.